Posts Tagged 'bigtrak'


SHDC#9 gave us a suprising amount of activity, in contrast to the general procrastination of #8. So, lets get started…

Jonny brought along an impressive collection of Psion 5’s (and an Oscilloscope he managed to aquire! Great work!). It seems they come to him to die. Apparently most die because the flex cable between the screen and base breaks.

Psion, Anyone?

We all spent a lot of time admiring the design; the Psion 5 keyboard and mechanism is just awesome. So why didn’t Psion do that well? The story appears to be that the products were too good, so no one upgraded!

The keyboard got pulled apart, again revealing some nice design. His plan is to reverse engingeer it to the point of being able to make it in to a USB or Bluetooth keyboard. I can see why; it really is one of the nicest small form factor keyboards i’ve ever tried.

I got to work trying to fix the remaining problems left over from my previous attempts to Bring Back the Big Trak. The main thing was that only half the keyboard was working, which was due to one of the traces on the flex connector having been corroded away. These things seem to be the casue of lots of problems!

Big Trak keyboard connector fix

The fix I used was to draw a new trace using a Conductive Pen. Not the most easy thing to use (you end up dabbing a lot rather than drawing), but it does the trick. Behold, the Big Trak is Back!

Leif brought along his new toy, a Beagleboard, which he was setting up to be accessibly over a serial terminal as there was no appropriate monitor around.


I then got interested in ways of providing remote access to it, so started looking around at VNC implementations. The thing I wanted to find out was whether there were any Java based VNC clients to allow it to be done as an applet from the clients perspective. Turns out there are! I tried RealVNC first, but couldn’t get it working straight away, so tried TightVNC. This gave much better results. The laptop on the right is running the server, and the left is the Java client:

Sweet. Now we just need to get TightVNC up on the Beagleboard!

Somehow during general tools talk and other fix-the-world discussions, ENSO and Quicksilver came up. These are basically applications designed to help invoke stuff from the keyboard quickly. ENSO was the one I tested out; one key feature is it’s ability to calculate the result of an expression that is highlighted, and replace it with the answer. Interestingly, it takes over and is invoked by holding down CAPSLOCK. Makes you realise how you never use that key, and it usually only features as an annoyance when you hit it by mistake!

It is an interesting thing to play with, and it certainly shows how easy it can be made to get to what you want. Emilio even wrote an ENSO Python Extension Wrapper for it. I’ll be trying out Quicksilver on the Mac too.

In another random discussion about something, Jonny mentioned the concept of “Bookmarklets”. These are bookmarks in your browser that are actually Javascript that is run. That means go to any page, click the link and the Javascript is invoked on that page. Now it is obvious these have been around a while with things like digg/blog this etc, but i’d never really come across them or thought about them. A really good example of it in use is Shared Copy. I can see these Bookmarklets have some great potential applications, and i’m sure there are some that haven’t been thought of yet.

The downside is the bookmark field itself naturally limits the amount of Javascript. As an experiment I did a little “Hello World!” Bookmarklet, but made it such that it just dynamically loads a script from a remote URL (script loading has no problems with cross-site urls). This means you can write the bookmarklet just as a .js file on the web, with no size limitations. I put it up at Hello World! Bookmarklet Example; go have a look!

Henry brought his new Bluetooth modules along that he had got from Round Solutions (ordered by fax!). The modules were BlueNiceCom IV based on the National LMX9830.

The main task appeared to be breaking it out to make it useable (bluetack it upside-down to something and solder on wires), then deciphering the datasheet to understand how to make it play. Getting the conections and config are easy when you know how, but they certainly appeared to make it hard to know how. But once it was responding, we had it pairing and talking to a mobile phone in no time. Even sending a text message. Check it out!

And by 2am, we were all wrapped up; not bad for a days work! I think the cake helped.

See you all at the next SHDC!


Bring Back the Big Trak!

For this one, there are two stories to this title…

1) Robotics in Schools Sucks! Bring Back The Big Trak!

I can remember when I was at primary school, one of the teachers sons brought in a “Big Trak”. For those who haven’t heard of Big Trak, let Peter explain!

This was great, and let people play with some programming basics. It was a time when teaching things like Logo was popular, based primarily on the Constructionist Learning work of people like Seymour Papert. I’ve managed to get hold of his “Mindstorms” book on Ebay, so am looking forward to reading it having had a great time reading a similar era book, “The Mighty Micro”.


After playing with Big Trak, I was pretty inspired and went away to built my own turtle. The result was a 2 motor wheeled block thing with a felt tip pen down a tube in the middle on a winch. This was to allow it to do “pen up” and “pen down” so it could draw on a big sheet of paper on the floor. And it had a big umbilical cord to a relay board I built for the BBC Micro our primary school had. And you’ve guessed it, I programmed a control program in our old favourite, BBC Basic! Awesome!

So, however many years later, I recently went in to a secondary school to help SETPoint run an activity day. It turned out I was teaching a class of around 30(!) about robots. The task was to build some kits, program them, and write a presentation. Having never seen the kits before in my life, or taught a full class, I have to say I was a little nervous/suprised when it became clear what I had signed up for!

Hex Walker IQ2 Board

It all went ok, but I have to say I was shocked by the kit being used. Everyone built a robot kit in groups of about 4, and these kits were pretty poor quality and obviously overused (partly to do with the cost of kitting out so many kits no doubt; there were 3 other classes!). They were basically fiddly gearboxes obviously intended for one-time assembly; they were un-reliable, had gears jamming, wires breaking off, broken parts, fell apart due to them being held together with a rubber-band assembly, etc. If ever you wanted an example of why good engineering pays off, you got it loud and clear from the frustration of the students.

The programmable controller also wasn’t intuatitive; there was no real sense of programming in a sequence of instructions, the motors had to be going while programming, it repeated the commands over and over so it was confusing what it was doing, and anytime you wanted to change it, everything was erased. It left all the students pretty confused and underwhelmed, and to add insult to injury, they had to dissassemble everything leaving many having felt they hadn’t achieved anything.

The shock and dissapointment for me was really that after 20 years, given all our advances in technology, we seemed to have gone backwards from Big Trak. There is no real excuse for such poor execution of teaching quite simple concepts. And it should be great fun!

2) Look What I Found! Bring Back The Big Trak!

Now this is pretty cool. Two weeks later, I’m helping run an after school club at a different place, and the head of D&T gives me a tour. They’ve got pretty cool stuff in some schools now; things like laser cutters! Anyway, whilst in the store room these places always have, enjoying the sawdust filled air, what do I spot on the shelf. Yes, that’ll be a Big Trak that will!

Obviously my exceitment must have been a little supprising to them, and it got better; I quickly found myself as the new owner! Thanks! I was warned it was broken, but where would the fun be otherwise!

On getting it home, I went to put some batteries in and was meet with big lumps of battery acid. This is some of the contacts, after I had knocked off a lot of it!

Big Trac Battery Damage

The acid had got everywhere, and after applying power directly, it was obviously dead. Time to get it apart. Here are the basic body components once i’d got the top off and all the circuit boards out:

Big Trac Case Parts

I replaced the main batteries with a 4AA battery pack. I needed to add a centre tap, as it turns out they use a split rail; this is so they can use half the number of transistors to get both directions! Soldering was really hard, and I had to clock up quite a temperature on the iron to get the old solder to melt. Anyway, the result was as follows…

It is somewhat alive! But only half the keyboard works, and perhaps more importantly, it doesn’t move! The reason i’m pushing it is to see if the movement sensor is working. There is a light/sensor pair spanning a cog with holes in it in one of the motor drives; after pushing it you can see it thinks it has got to the end of it’s sequence, so that confirms that bit is working!

Some more fudging got the power to the motors; the main powerswitch was totally corroded, so I just bypassed that.

In this demo, I had to be a bit selective about what keys to press as only half were working, but getting there! I think there is life in the Big Trak yet! More to come…